The initial kinetic energy of the boat and its rider is
After Sam stops it, the final kinetic energy of the boat+rider is
because its final velocity is zero.
For the law of conservation of energy, the work done by Sam is the variation of kinetic energy of the system:
where the negative sign is due to the fact that the force Sam is applying goes against the direction of motion of the boat.
Because dogs have their bodies covered with fur, sweating is less effective. Dogs have sweat glads in places where there is little fur. However this is not enough in some hot days. To keep the body temperature in order dogs have to rely on panting. The interior of mouth and lungs is wet, so breathing quickly speeds up cooling. It acts similarly to wind blowing on sweaty person's skin.
You can try it on your own. When you breathe heavily you will feel coolness :)
In order to evaporate (change state from liquid to gas) heat energy has to be delivered to water. The heat energy is taken from the body of dog, thus cooling it.
According to law of conservation of mass within a reaction,
The mass of the compound formed is (23+35.5) grams means 58.5 grams of sodium chloride[NaCl] will be formed.